Anything excess is not advised. Excess food intake creates lot of health problems. Excess property drowns us into strains and stresses. Excess size of cloths makes our appearance awkward.
A patting or a praise will definitely give us encouragement. But a limitless praising called flattery appears indecent and unusual in public. The magic of flattery is the receiving person does not decline the comment and the audience dare not to stop it. Everybody knows that the targeted person is being carried away by the praising people and they are expecting a favor from him.
The benefits of flattery can be achieved and are required too when encouraging children while teaching them habits and education. It should be stopped at an age when the child attains age of understanding the difference between a praise and flattery.
Active propagation of flattery can be seen in political activities and official promotions. We cannot deny the closeness of bribery with flattery.